#include <iostream>
#include <vector>
#include <algorithm>
#include <math.h>
#include <unordered_set>
#include <queue>
#include <string>
#include <bits/stdc++.h>
using namespace std;
int main()
{
int n, m;
cin >> n >> m;
vector<vector<int>> adj(n+1);
for (int i = 1; i <= m; i++)
{
int a, b;
cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
}
unordered_set<int> zsakok;
for (int i = 0; i < adj.size(); i++)
{
if (adj[i].size() == 1)
zsakok.insert(i);
}
vector<int> zsakfalu(zsakok.begin(), zsakok.end());
int megnezve = 0;
queue<int> sor;
vector<int> megold(0);
for (int i = 0; i < zsakfalu.size(); i++)
{
sor.push(zsakfalu[i]);
vector<bool> check(n + 1);
vector<int> path(0);
path.push_back(zsakfalu[i]);
bool vege = false;
while (sor.size() != 0)
{
int most = sor.front();
sor.pop();
//cout << most << " ";
for (int x : adj[most])
{
if (!check[x] && x != most && !vege && adj[x].size() < 3)
{
sor.push(x);
path.push_back(x);
check[x] = true;
check[most] = true;
}
else if (!check[x] && adj[x].size() <= 3 && !vege)
{
sor.push(x);
path.push_back(x);
check[x] = true;
check[most] = true;
vege = true;
break;
}
}
megnezve++;
}
for (int x : path)
{
megold.push_back(x);
}
}
cout << megold.size() - zsakfalu.size() << endl;
sort(megold.begin(), megold.end());
for (int y : megold)
{
if (find(zsakfalu.begin(), zsakfalu.end(), y) == zsakfalu.end())
{
cout << y << " ";
}
}
}